A series of prepared traffic noise signals, each of 20 minutes in duration, were evaluated indoors by a jury of adult listeners. All noise tapes exhibited a Gaussian distribution of random noise events with a wide range of mean levels and standard deviations included. The main purposes of the experiments were to study the applicability and the limitations of the Noise Pollution Index, especially at higher standard deviation values, and to estimate a psychological time constant for varying traffic noise climates. It appears that the energy mean term (Leq) in the Noise Pollution Index tends to overestimate the subjective effect of the higher noise levels present in the overall traffic noise climate. When the standard deviation of the traffic noise exceeds 6.0, the subjective annoyance was found to decrease rapidly with further increases in the deviation for cases where Leq is held constant. For cases where the noise level mean (mu) is held constant, the preceived annoyance increases continually with the standard deviation of the signal. The present data indicates that the perceived annoyance of traffic noise signals having a Gaussian distribution of peaks may be well approximated by an index of the form mu Ksigma, where K equals 0.5 and sigma is the standard deviation. This formulation offers much better correlation than the Noise Pollution Index, especially at larger values of standard deviation (sigma greater than 6). It is tentatively concluded that the psychological time constant for traffic noise is at least as large as 7 minutes.

  • Corporate Authors:

    University of Toronto

    Institute for Aerospace Studies, 4925 Dufferin Road
    Toronto, Ontario  Canada  M5S 1A1
  • Authors:
    • Johnston, G W
    • Carothers, R
  • Publication Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 00083854
  • Record Type: Publication
  • Report/Paper Numbers: Number 24 Res. Rpt.
  • Files: TRIS
  • Created Date: May 29 1975 12:00AM